--- a/src/java.base/share/classes/java/util/Comparators.java	Wed Oct 09 09:57:41 2019 -0700
+++ b/src/java.base/share/classes/java/util/Comparators.java	Wed Oct 09 10:17:50 2019 -0700
@@ -66,6 +66,7 @@
         private static final long serialVersionUID = -7569533591570686392L;
         private final boolean nullFirst;
         // if null, non-null Ts are considered equal
+        @SuppressWarnings("serial") // Not statically typed as Serializable
         private final Comparator<T> real;
 
         @SuppressWarnings("unchecked")